


Rainy Day

by SonicaSpeed123



Category: Undertale (Video Game)
Genre: Ecto-Vagina, Ecto-dick, Fluff, M/M, NSFW, Riding, ecto-parts
Language: English
Status: Completed
Published: 2017-02-06
Updated: 2017-02-06
Packaged: 2018-09-22 09:04:51
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,527
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9599180
Author URL: https://archiveofourown.org/users/SonicaSpeed123/pseuds/SonicaSpeed123
Summary: It didn't rain often in Snowdin, being primarily snowy and all, but when it did, Sans and Papyrus had to find their own ways to entertain themselves.(sex, we're talking about sex here. also a cake.)





	

**Author's Note:**

> Okay so this one has a strange origin. It was raining like balls outside one day, so I was super confused when my friend showed up at my door like ‘yeah i just walked like miles to get here can i stay for a bit til my bf comes to get me’ and i didnt really know what else to say but sure?? Anyways we made a cake and it was great and i thought of this because fontcest.

By the time Papyrus got home, he was completely soaked.  It didn’t rain in Snowdin, but occasionally, sleet and slush would make being outside miserable for the monsters living there.  When Sans looked out the window and saw that the usual light and fluffy snow had turned to the gross brown and wet chunks, he called Papyrus and demanded that he come home as soon as possible.

Unfortunately, he was too late.  There wasn’t a dry bone in Papyrus’s body at this point, and if he kept tracking in the slush like this, there wouldn’t be a dry spot on the carpet, either.

“Wet feet! Take off your shoes!”

Papyrus groaned, but bent down to remove his sneakers.  And his socks.  And he started taking off his pants.

“Woah, woah, what are you-!?”

“sans, i’m soaking wet, and i just wanna get out of these clothes.”

“Don’t just strip naked out here! C’mon, go to your bedroom for that!”

“alright, fine.” Papyrus rose and took his shoes while he trudged up the stairs, shooting a smirk at his brother before heading into his room.  When he came back out, he was wearing nothing but a bathrobe, carrying his hoodie and pants in his hands.  They dripped water onto the carpet, almost defeating the purpose of changing in the first place.

“Papy. Why aren’t you wearing clothes?”

“need to do laundry. nothin’ left. i’ll just toss these in the dryer.”  Papyrus, now dry, practically bounded down the stairs with energy Sans wished he had.  How could a skeleton so lazy have such infinite energy? Maybe he just didn’t use as much normally, so he seemed like he had more? At the moment, however, these thoughts were in the back of Sans’s mind, because the tiny bath robe just barely covered his younger brother’s pelvic area.

Shaking those thoughts away, he turned to the television.  He shouldn’t think about stuff like that if Papy wasn’t explicitly showing himself off to him, right?  Dirty thoughts were invasive and quite rude, even if his brother didn’t know he was thinking them.

Papyrus returned and dropped into the spot on the couch next to Sans.  Without a word, he leaned into Sans, seemingly to leech his warmth from him.  That robe couldn’t be doing much to keep him warm.  Accepting this fate, Sans turned his head and pressed into Papyrus’s body, letting him wrap his arms around the smaller skeleton.  Comfortable silence went on for a while, and Papyrus seemed to be enjoying the reruns of game shows, chuckling every time the contestant gave a stupid answer.  Sans didn’t pay much attention to the television, instead directing his thoughts toward his brother.  His hands and arms were cold, and his nasal bone was tinted a honey orange.  He kept bobbing his knee up and down, as if sitting still was a challenge.  His breathing was a bit quick as well.  Sans wondered if his soul was feeling strange.  Maybe he just needed to move around a bit?

The rerun ended and rolled into a commercial break.

“Hey, Papyrus…”

“hm?”

“You wanna do something? You seem kinda… jittery.”

“oh, uh… sorry, i’m just usually still out right now. what do you want to do?”

Sans smiled and looked up at his brother, “Let’s make something to eat!”

“i dunno, bro… i’m not much of a chef. not even in the mood for tacos…”

“Well, I didn’t say it had to be tacos! We could try baking something, too. I got cake mix for your birthday, but I can just buy more later.”

“do we even have frosting?”

“We’ve got peanut butter, powdered sugar, and butter. We can make some from scratch!”

Papyrus gestured toward the television, “the next episode’s starting soon…”

“Oh, c’mon, would you really rather sit here for another half hour?” Sans would have raised an eyebrow, knowing his brother wouldn’t be able to sit still for much longer.

“...nah… m’kay, let’s do it.”

 

Sans turned the T.V. off and moved into the kitchen, already listing out what they needed in his head.  He started taking the ingredients out of the fridge and told Papyrus to get a bowl, a cake pan, and the hand mixer. After hearing a grunt of affirmation, he started digging through the silverware drawer for the measuring cups.

When he looked up again, he got an eyeful of his brother’s pelvis.

Papyrus was standing on the counter to reach for the higher cabinets, where the hand mixer would be, and he didn’t seem to notice that he was basically teasing his older sibling.

“Wh- Papy!!”

“huh?” Papyrus looked down at Sans.

“You’re not wearing any underwear!” Sans’s face flushed to match his magic.

“pff- you’ve already seen everything i’ve got, big bro. and then some-”

“Well- N-Now isn’t sexy time!! How am I supposed to work when you look so…”

“...so..?”

“A-ANYWAYS-” Sans turned on his heel and started to crack the eggs into a bowl.

Papyrus laughed aloud, “aww, i’m sorry, okay? c’mon, sansy, y’know i love you.”

Sans puffed in frustration, “I love you, too.”

 

Somehow, the two managed to get more than half the batter into the oven.  The rest had been used for ‘taste testing’, which obviously meant that each of them had to take at least two… maybe three spoonfuls of it.  To make sure the batter was edible! And that neither of them had poisoned it!

...Okay, maybe they were both a little impatient.

Which probably wasn’t the best thing, now that they had to wait for the cake to bake.

The brothers sat on the ground next to the oven, bored out of their minds.  Sans eventually resorted to holding Papyrus’s hand and running his phalanges across his metacarpals, taking in how smooth they were.  His own had been scraped across many times by magic attacks in his training, so his bones tended to be more rough where they healed over. His brother’s broad, almost soft bones had a way of fascinating him.

Papyrus hummed in satisfaction, looking down at his older brother with admiration and love.  The noise snapped Sans back to reality, and he blushed at the sound.  How long had he been doing that?

Throwing all caution to the wind, Sans leaned up to peck a kiss on Papyrus’s cheekbone.  When he slumped back into his position in his brother’s arms, Papyrus chuckled and returned it on his forehead.

“i love you.”

Sans closed his eyes and leaned back into Papyrus’s chest, “Love you too, Papy…”

Papyrus was getting antsy again.  He started tapping his fingers against the floor tile, bouncing his leg in time to some imaginary beat.  Sans couldn’t help but notice how the robe slipped just shy of where his pelvis was, as if some deity was keeping the beautiful sight from Sans’s eyes.

He shook his head again.  Thinking like that was creepy.  Quit it.  This moment wasn’t sexual.  It was time for some peaceful snuggling.  Nothing more than that.

Papyrus’s hands started wandering.

Only slightly, at first.  The arm around Sans’s shoulder started rubbing small circles into his scapula, like a charmingly half-assed massage, but his other arm moved to mimic the other’s action near his false ribs.

“Ah… Papy?”

“hm?” the hand at his scapula moved towards his spine and traveled down to his floating ribs.

“Are you, uh… trying to tell me something here..?”

“what d’ya mean, bro?” his fingers brushed against Sans’s sensitive floating ribs, sending a shiver through him. Papyrus couldn’t help but grin at the reaction he got, dragging a hesitant whimper from his older sibling.

“I- I mean- Do you want to… U-um… Take this upstairs..?”

Papyrus stopped moving, but looked down at his brother with patience and kindness in his eyes, “do you?”

Sans’s eyelights flickered down to between Papyrus’s legs, “A little bit… Only if you want to…”

“wouldn’t be doin’ this if i didn’t want to, love.” His hand gently wrapped around one of Sans’s floating ribs through his shirt.

“Ah- W-well, in that case,” Sans stood up and offered his hand to help his brother up, “Then yes. I would love to do this with you.”

Papyrus blinked, thrown off by the sudden boost in confidence Sans had, but smiled and took his brother’s hand, then was led upstairs to Sans’s bedroom.

 

With a soft thunk, Papyrus sat down on Sans’s bed.  The smaller skeleton quickly scrambled into his lap, wrapping his arms around his brother’s neck and leaning in to kiss him.  Papyrus opened his mouth to let Sans’s tongue in and reached behind him to gently graze his fingers over his vertebrae, savoring the warm, almost dark taste of his pale blue magic. The contrast between the color and the flavor once surprised Papyrus, but now he treasured it, drinking up every moment he could indulge in it.

Even now, Papyrus struggled to keep still, practically squirming in anticipation until Sans pushed him backwards to land his head on one of Sans’s pillows.  Breaking the kiss, Sans leaned back to give his brother a smug glare.

“You’re so impatient, Papy.  We’ll get there, okay?”

“okay, okay… i just can’t help it, bro. you’re too perfect…”

“Aww, you,” Sans closed the distance between them, nuzzling his face against Papyrus’s neck, “Such a sweetheart.  You’re still far too antsy, though…” 

Papyrus felt Sans’s tongue swipe across his neck, “ah-!”

“Let’s get rid of some of that energy, shall we?”

“s-sounds like a plan…”  Papyrus couldn’t help but shiver at Sans’s tone.

 

Sans hopped off the bed to strip naked before his brother, slowly showing off every curve in his bones, knowingly teasing Papyrus. The taller skeleton almost whined from his spot on the bed, desperate to have him closer.  After what felt like an eternity, Sans climbed back on top of Papyrus and started to untie the belt around the bath robe’s waist, inching ever so slightly forward.  Once the belt was gone, Papyrus easily slid out of the rest of the robe.  For a few moments, Sans simply looked at his sibling’s body, examining every exquisite feature in his little brother’s bones.  Finally, he smiled and kissed Papyrus again, this time for only a moment before sitting up.

“Are you comfortable, Papy?”

Papyrus hummed as Sans gently pressed his hand against his sternum, “yeah, you can go ahead, i’m ready.”

There was a sudden chill that slowly melted into a pleasant buzzing sensation as Sans used his magic.  Papyrus’s instantly responded, resonating with the signal and spreading a warm feeling through his entire body.

“Is this good?”

“y-yeah, yeah, s’good…” Papyrus’s eyes fell half-closed, the honey orange color on his face growing more intense.

“Golly…” Sans whispered, nearly wonderstruck, “Y-you can form your… whatever you choose now, if you like…”

He didn’t have to ask twice. The moment Papyrus’s eyes closed completely, his aroused magic collected in his pelvis and shaped into his dick. Sans realized that maybe he had inched a little too closely to his brother’s pelvis- his cock was pressed right up against the buzz of his own arousal.

“ _ ohhh… _ ” Papyrus thrusted upwards, desperately searching for contact with his lover’s magic.

“Ahh- Oh, God…” The friction turned the pleasant buzz into a more intense desire, forcing Sans’s magic to shape his vagina.

“sans,  _ saaans… _ ” Papyrus whined, already barely coherent.

“I know, I know, I want it too.  Just…” Sans lifted off of his brother, hovering over his cock. Slowly, agonizingly so, he guided the cock into himself, suppressing his moans so he could hear the other’s.

“ _hah-_ ah, hnn- s-sans, holy-! nnn, _fuck_ , _you’re_ _so good-_ ”

When he was fully seated, Sans gasped for air.  “Nnn… Watch your language, Papy… B-be a good boy, now…”

Papyrus twitched at the praise, “god,  _ god _ , sans,  _ please _ move- need it-”

“Don’t worry, Papy, I’ve got you…”  Adjusting his legs, Sans pulled back up until his brother’s dick was no longer inside him, then steadily slid back down.  He couldn’t help but groan and pant this time, feeling his lover’s magic reacting to his own wherever they touched.  He was barely able to keep his eyes open, but the way Papyrus looked when he did this…

He looked absolutely destroyed every time.  His face was colored completely orange, sweat trailing down his cheekbones, his jaw slightly agape, not even trying to restrain his voice or his reactions.  God, his voice.  It shook and cracked when Sans brushed up against his sensitive spots, lowered seductively when he was hard, and peaked when he was getting close to cumming.  Sans wondered if his own voice betrayed him the same way.

Sans was starting to get comfortable with this pace, so he gradually began to move faster.  Papyrus’s reaction was instant, throwing his head back against the pile of pillows and moaning loudly, gripping the sheets to ground himself in reality as his soul felt like floating away with his pleasure.

“sans, that- you always feel so-  _ hnng- _ ! oh,  _ fuck me _ , so good..! more, more,  _ yes _ !”

“L-Language,” Sans giggled, but moved a bit faster, “A dirty mouth means a dirty mind.”

“if that were- ahh- if that were true, you’d curse a lot more, sansy…”

“You think- hah- that I have a dirty mind, Papy? Oh, I’ll show you- nngh- just how naughty I can be, brother…”

Sans could feel his lover shiver under him in anticipation as he pulled himself closer to Papyrus, perching by his neck and just barely grazing his mandible.

“Ohh, Papy… Your cock feels  _ so _ damn  _ good _ inside my cunt, agh- I’m gonna make you feel so good, I’m gonna make you cum inside me-” Sans whispered, stunning his brother into silence as he squirmed again.  “You like the thought of that, huh? The thought of feeling that beautiful pressure finally release deep inside me-  _ hah, fuck _ \- You want that, don’t you?”

“ _ sans- _ ” Papyrus gasped.

“ _ God _ , I want it too- Oh,  _ Papyrus _ , you’re so close, I can  _ feel _ it-  _ Cum _ , Papy, cum inside- Wanna feel your hot magic leaking out of my pussy- do it, baby, do it, I love you-”

“l-love-  _ fuck- _ ! g-gonna-! cum,  _ cumming-- _ !”

“ _ Hnn- _ ! Pap-!” Sans peeped as his voice gave out, feeling his lover’s essence blossom warmly and spread inside him as his orgasm finally took him.  They both stilled and stiffened, letting their pleasure wash over them together, until they suddenly collapsed.  They stayed for a while, breathing roughly and trying to calm their souls.  Eventually, Sans shifted enough to pull his brother’s dick out of himself and sat back enough to see Papyrus’s face. 

His eyes were closed, but he was still breathing hard, sweat dripping down the sides of his face.  His cheekbones were bright orange with blush, and drool of the same color leaked out from his jaw.  Sans smirked, wiped it off, then kissed him, falling beside him to rest.

“sans…” Papyrus mumbled, turning to face him.

“Felt good..?”

“amazin’...” He reached out and pulled Sans’s body flush with his to snuggle.  Quickly, the warmth of his brother’s body soothed him enough to fall asleep.  Papyrus followed soon after.

  
The next day, they found that the cake had burned.


End file.
